Method for removing TOC in industrial-grade hydrogen peroxide solution

Abstract

The invention provides a method for removing TOC (Total Organic Carbon) in an industrial-grade hydrogen peroxide solution, which comprises the following steps: S1, carrying out heat exchange on the industrial-grade hydrogen peroxide solution produced at the bottom of an extraction tower and pure water to enter the extraction tower through a heat exchanger, and further cooling to 15-25 DEG C through a low-temperature water cooler; s2, filtering the hydrogen peroxide solution cooled in the step S1 through a high-precision filter with the pore diameter of 1 mu m; s3, introducing the hydrogen peroxide solution filtered in the step S2 into a first-stage hydrophilic oleophobic coalescer for coalescence separation, so that the TOC content is reduced to be not greater than 100 ppm; s4, introducing the hydrogen peroxide solution treated in the step S3 into a secondary hydrophilic oleophobic coalescer for further coalescence and separation, so that the TOC content in the hydrogen peroxide solution is further reduced to be not greater than 80ppm; s5, recovering an oil phase; and collecting the oil phase TOC separated in the step S3 and the step S4, and conveying the oil phase TOC to the extraction tower for recycling. According to the method, TOC in hydrogen peroxide is efficiently removed, and meanwhile, the production cost and the environmental risk are remarkably reduced.

Description

Technical Field

[0001] The invention relates to a method for purifying a hydrogen peroxide solution, in particular to a method for removing TOC from an industrial-grade hydrogen peroxide solution, and belongs to the technical field of chemical production. Background Art

[0002] Hydrogen peroxide is an important chemical raw material and oxidant, widely used in chemical synthesis, papermaking, textiles, electronics, food, pharmaceuticals and other fields. Currently, industrial-grade hydrogen peroxide is mainly produced using the anthraquinone process. During the anthraquinone production process, various impurities are inevitably introduced into the product, including dissolved inorganic impurities (such as metal ions, phosphate ions, and water-soluble organic matter) and entrained organic impurities (such as residual anthraquinone, anthraquinone derivatives, esters, and heavy aromatics). These organic impurities are collectively referred to as total organic carbon (TOC).

[0003] In existing technology, TOC removal from industrial-grade hydrogen peroxide solutions primarily relies on extraction with heavy aromatic solvents. Although widely used in industrial production, this method still has significant drawbacks. Extraction efficiency is easily affected by various factors, including production conditions, working fluid properties, flow rate, and interface control, resulting in significant fluctuations in the TOC content of the product. The extraction process consumes significant amounts of heavy aromatic solvents and generates significant amounts of waste aromatics, increasing raw material and waste disposal costs. Traditional extraction methods typically require relatively high temperatures of 35-45°C, which not only increases the solubility of TOC in the aqueous phase, resulting in poor removal efficiency, but also allows free heavy aromatics to be carried over into the product. High temperatures also reduce the thermal stability of hydrogen peroxide, increasing the risk of product decomposition and compromising process safety. Furthermore, the TOC content of the hydrogen peroxide product after extraction is often still high, failing to meet the stringent requirements for caprolactam, HPPO propylene oxide production, and food-grade and electronic applications. Consequently, to meet these more stringent TOC requirements, many companies have been forced to install additional purification equipment, significantly increasing production costs and safety risks.

[0004] Therefore, there is an urgent need to develop an efficient, stable and environmentally friendly industrial-grade hydrogen peroxide TOC removal method to replace the traditional heavy aromatic hydrocarbon solvent extraction process. Summary of the Invention

[0005] Based on the above background, the purpose of the present invention is to provide a method for removing TOC from industrial-grade hydrogen peroxide solution, which adopts a new hydrophilic and lipophobic agglomeration technology to efficiently remove TOC from hydrogen peroxide while significantly reducing production costs and environmental risks.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A method for removing TOC from an industrial-grade hydrogen peroxide solution, the method comprising the following steps:

[0008] S1, cooling treatment: the industrial-grade hydrogen peroxide solution produced at the bottom of the extraction tower is heat exchanged with the pure water to be entered into the extraction tower through a heat exchanger, and then further cooled to 15-25°C through a low-temperature water cooler to reduce the solubility of TOC in the hydrogen peroxide solution;

[0009] S2, microfiltration treatment: filtering the hydrogen peroxide solution after cooling in step S1 through a high-precision filter with a pore size of 1 μm to remove some free TOC and particulate impurities;

[0010] S3, a primary coalescence treatment; introducing the hydrogen peroxide solution filtered in step S2 into a primary hydrophilic oleophobic coalescer, and coalescing and separating the oil phase TOC in the solution from the aqueous phase hydrogen peroxide solution by the coalescing material in the primary hydrophilic oleophobic coalescer, thereby reducing the TOC content in the hydrogen peroxide solution to no more than 100 ppm;

[0011] S4, secondary coalescence treatment; introducing the hydrogen peroxide solution treated in step S3 into a secondary hydrophilic and oleophobic coalescer for further coalescence separation by a coalescing material, so that the TOC content in the hydrogen peroxide solution is further reduced to no more than 80 ppm;

[0012] S5, oil phase recovery: collect the oil phase TOC separated in step S3 and step S4 and transport it to the extraction tower for reuse.

[0013] Preferably, the agglomerated material is prepared from the following components:

[0014] Polypropylene, polyester, glass fiber or a mixture thereof as the skeleton material, accounting for 40 to 70% of the total weight of the agglomerated material;

[0015] Polyvinyl alcohol, hydroxymethyl cellulose or silicate as the hydrophilic component, accounting for 10 to 25% of the total weight of the agglomerated material;

[0016] Polytetrafluoroethylene, polyvinylidene fluoride or perfluoroallyl ethyl ether as the oleophobic component, accounting for 15 to 35% of the total weight of the coalescing material;

[0017] The surfactant, pH regulator or antioxidant is used as a functional additive, accounting for 2 to 10% of the total weight of the agglomerated material.

[0018] Preferably, in step S2, the filtration pressure of the high-precision filter is 0.2-0.3 MPa, and the filtration flow rate is 20-25 m / h.

[0019] Preferably, in step S3, the liquid residence time of the first-stage hydrophilic-oleophobic coalescer is 15 to 25 minutes, and the operating pressure is 0.15 to 0.25 MPa.

[0020] Preferably, in step S4, the liquid residence time of the secondary hydrophilic-oleophobic coalescer is 10 to 15 minutes, and the operating pressure is 0.1 to 0.2 MPa.

[0021] Preferably, the method for removing TOC in an industrial-grade hydrogen peroxide solution further includes a regeneration step of the coalescing material, the regeneration step including backwash regeneration and chemical cleaning regeneration, the backwash regeneration being performed when the pressure difference of the primary hydrophilic and oleophobic coalescer or the secondary hydrophilic and oleophobic coalescer increases to 1.5 times the initial value, and the coalescing material is reversely flushed with hot water at 50 to 60° C. for 30 to 60 minutes, and the chemical cleaning regeneration sequentially uses a nitric acid aqueous solution and a hydrogen peroxide solution to clean the coalescing material.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The present invention discloses a method for removing TOC from an industrial-grade hydrogen peroxide solution. The method can reduce the TOC content in the industrial-grade hydrogen peroxide to below 80 ppm through a combined process of cooling-filtration-two-stage coalescence. The cooling operation of the method improves the thermal stability of the hydrogen peroxide and reduces the risk of decomposition. The coalescence removal process of the method is less affected by external factors, and the product quality is stable and reliable. The method does not generate a large amount of waste liquid, and the coalescence material can be recycled and reused, thereby reducing the amount of hazardous waste to be processed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0025] Figure 1 This is a schematic flow diagram of a method for removing TOC from an industrial-grade hydrogen peroxide solution of the present invention;

[0026] Figure 2 This is a system schematic diagram of a method for removing TOC from an industrial-grade hydrogen peroxide solution according to the present invention;

[0027] In the figure: 1. Extraction tower; 2. Heat exchanger; 3. Cooler; 4. High-precision filter; 5. First-stage hydrophilic and oleophobic coalescer; 6. Second-stage hydrophilic and oleophobic coalescer; 7. Aromatic hydrocarbon recovery tank; 8. Aromatic hydrocarbon transfer pump. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0029] In the present invention, unless otherwise specified, all parts and percentages are by weight. The equipment and raw materials used are commercially available or commonly used in the art. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are all universal standard parts or components known to those skilled in the art. Their structures and principles are known to those skilled in the art through technical manuals or routine experimental methods.

[0030] The following detailed description of the embodiments of the present invention is made in conjunction with the accompanying drawings. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments may be implemented by those skilled in the art without these specific details.

[0031] like Figure 1 As shown, an embodiment of the present invention discloses a method for removing TOC from an industrial-grade hydrogen peroxide solution, the method comprising the following steps:

[0032] S1, cooling treatment; the industrial-grade hydrogen peroxide solution produced at the bottom of the extraction tower 1 is heat exchanged with the pure water to be entered into the extraction tower 1 through a heat exchanger, and then further cooled to 15-25°C through a low-temperature water cooler 3 to reduce the solubility of TOC in the hydrogen peroxide solution;

[0033] S2, microfiltration treatment; the hydrogen peroxide solution after cooling in step S1 is filtered through a high-precision filter 4 with a pore size of 1 μm to remove some free TOC and particulate impurities. The filtration pressure of the high-precision filter 4 is 0.2-0.3 MPa, and the filtration flow rate is 5-15 m / h;

[0034] S3, primary coalescence treatment; the hydrogen peroxide solution filtered in step S2 is introduced into a primary hydrophilic oleophobic coalescer 5, and the oil phase TOC in the solution is coalesced and separated from the aqueous phase hydrogen peroxide solution by the coalescing material in the primary hydrophilic oleophobic coalescer 5, so that the TOC content in the hydrogen peroxide solution is reduced to no more than 100 ppm; the liquid residence time of the primary hydrophilic oleophobic coalescer 5 is 15 to 25 minutes, and the operating pressure is 0.15 to 0.25 MPa;

[0035] S4, secondary coalescence treatment; the hydrogen peroxide solution treated in step S3 is introduced into the secondary hydrophilic oleophobic coalescer 6 for further coalescence separation by the coalescing material, so that the TOC content in the hydrogen peroxide solution is further reduced to no more than 80 ppm; the liquid residence time of the secondary hydrophilic oleophobic coalescer 6 is 10 to 15 minutes, and the operating pressure is 0.1 to 0.2 MPa;

[0036] S5, oil phase recovery; collect the oil phase TOC separated in step S3 and step S4 and transport it to the extraction tower 1 for reuse.

[0037] The agglomerated material is prepared from the following components:

[0038] Polypropylene, polyester, glass fiber or a mixture thereof as the skeleton material, accounting for 40 to 70% of the total weight of the agglomerated material;

[0039] Polyvinyl alcohol, hydroxymethyl cellulose or silicate as the hydrophilic component, accounting for 10 to 25% of the total weight of the agglomerated material;

[0040] Polytetrafluoroethylene, polyvinylidene fluoride or perfluoroallyl ethyl ether as the oleophobic component, accounting for 15 to 35% of the total weight of the coalescing material;

[0041] The surfactant, pH regulator or antioxidant is used as a functional additive, accounting for 2 to 10% of the total weight of the agglomerated material.

[0042] Specifically, the preparation method of the agglomerated material is as follows:

[0043] Raw materials: 55 parts by weight of polypropylene fiber, 15 parts by weight of polyvinyl alcohol, 5 parts by weight of aluminum silicate, 20 parts by weight of polytetrafluoroethylene powder, 3 parts by weight of nonionic surfactant, and 2 parts by weight of antioxidant;

[0044] Mixing and dispersion: Dissolve polyvinyl alcohol in an appropriate amount of deionized water, heat to 90°C and stir to dissolve. Disperse polytetrafluoroethylene powder into a uniform emulsion with the aid of a surfactant. Add aluminum silicate powder to deionized water and ultrasonically disperse for 10 minutes. Mix the three dispersions, add antioxidant, and mix under high-speed stirring for 30 minutes.

[0045] Impregnation treatment: Cut the polypropylene fiber into appropriate lengths, pre-treat it with an alkaline solution to increase the surface roughness, immerse the pre-treated polypropylene fiber in the mixed dispersion, and immerse it under reduced pressure for 2 hours. Remove the impregnated fiber and control the liquid content to be 200-250% of the fiber weight;

[0046] Curing and molding: Place the impregnated fiber into a mold, pre-dry at 80°C for 4 hours, heat to 150°C, cure for 2 hours, cool to room temperature, and demould to obtain agglomerated material blank;

[0047] Post-processing: Cut the agglomerated material body into the required shape and size, soak it in 3% hydrofluoric acid solution for 10 minutes to enhance the surface oleophobicity, and finally rinse it thoroughly with deionized water and dry it at 60°C for 12 hours.

[0048] The prepared agglomerated material has the following characteristics: porosity of 75-85%, hydrophilic contact angle of 25-35 degrees, oleophobic contact angle of 110-130 degrees, and tensile strength of ≥2.5MPa.

[0049] When the hydrogen peroxide solution containing TOC passes through the coalescing material, due to the hydrophilic and oleophobic properties of the coalescing material, its surface will cause the dispersed tiny oil droplets to aggregate in the oleophobic area to form larger oil droplets. Due to the difference in oil and water density and surface properties, these coalesced oil droplets will separate from the water phase and float to the top of the coalescer for collection and discharge, while the hydrogen peroxide solution will pass through the filter element smoothly and be discharged from the clear liquid outlet at the bottom.

[0050] like Figure 2 As shown, the system employing this method for removing TOC from industrial-grade hydrogen peroxide solution includes, in sequence, an extraction tower 1, a heat exchanger 2, a cooler 3, a high-precision filter 4, a primary hydrophilic and oleophobic coalescer 5, a secondary hydrophilic and oleophobic coalescer 6, an aromatics recovery tank 7, and an aromatics delivery pump 8. The extraction tower 1 is used for preliminary purification in the anthraquinone process for hydrogen peroxide production. The heat exchanger 2 is used for heat exchange between the hydrogen peroxide solution and pure water. The cooler 3 is used to further reduce the temperature of the hydrogen peroxide solution. The high-precision filter 4 is used to filter particulate matter and some free TOC. The primary hydrophilic and oleophobic coalescer 5 performs the first stage of TOC coalescence and separation. The secondary hydrophilic and oleophobic coalescer 6 performs the second stage of TOC coalescence and separation. The aromatics recovery tank 7 collects the oil phase TOC separated by coalescence. The aromatics delivery pump 8 returns the collected oil phase to the extraction tower 1.

[0051] An industrial-grade hydrogen peroxide solution with a concentration of less than 38 wt% flows from the outlet of extraction tower 1 through a pipeline and enters the inlet of a heat exchanger 2. Pure water enters the other inlet of heat exchanger 2 through a pipeline, undergoing heat exchange with the hydrogen peroxide solution. After heat exchange, the purified water enters extraction tower 1 through a pipeline. The initially cooled hydrogen peroxide solution flows from the outlet of heat exchanger 2 and enters a low-temperature water cooler 3 through a pipeline for further cooling. Low-temperature cooling water enters cooler 3 through a separate pipeline, undergoing heat exchange with the hydrogen peroxide solution, and then exits through another pipeline. The hydrogen peroxide solution, cooled to 15-25°C, flows from the outlet of cooler 3 and enters a high-precision filter 4 through a pipeline. The filtered hydrogen peroxide solution flows from the outlet of high-precision filter 4 and enters the bottom inlet of a primary hydrophilic-lipophobic coalescer 5 through a pipeline. After the primary coalescing treatment, the hydrogen peroxide solution flows from the bottom outlet of the primary coalescer and enters the inlet of a secondary hydrophilic-lipophobic coalescer 6 through a pipeline. The oil-phase TOC separated by the primary coalescence flows out of the top outlet of the primary coalescer and enters the aromatics recovery tank 7 via a pipeline. The qualified hydrogen peroxide product, after secondary coalescence, flows out of the bottom outlet of the secondary coalescer and enters the subsequent product intermediate tank via a pipeline. The oil-phase TOC separated by the secondary coalescence flows out of the top outlet of the secondary coalescer and enters the aromatics recovery tank 7 via a pipeline. The collected oil-phase TOC flows out of the bottom outlet of the aromatics recovery tank 7 and enters the inlet of the aromatics transfer pump 8. Aromatics transfer pump 8 pressurizes the collected oil-phase TOC and transfers it back to the extraction tower 1 via a pipeline for reuse to maintain system solvent balance.

[0052] The method for removing TOC from an industrial-grade hydrogen peroxide solution further comprises a regeneration step of the agglomerated material, and the regeneration step comprises backwashing regeneration and chemical cleaning regeneration.

[0053] Backwash regeneration is performed when the pressure difference of the first-stage hydrophilic-oleophobic coalescer 5 or the second-stage hydrophilic-oleophobic coalescer 6 increases to 1.5 times the initial value. Hot water at 50-60°C is used to reversely flush the coalescing material for 30-60 minutes. Specifically, the coalescer's inlet and outlet valves are first closed to release the internal pressure. Hot water at 50-60°C is then introduced into the coalescer at a flow rate of 1.5-2 times the normal operating flow rate for a reverse flush of 30-60 minutes. Fresh water is then used to forward flush the coalescer for 10-15 minutes. Finally, normal operating conditions are restored.

[0054] Chemical cleaning and regeneration involves sequentially cleaning the coalescing material with aqueous nitric acid and then hydrogen peroxide solutions. First, close the coalescer's inlet and outlet valves and drain the liquid inside. Then, introduce a 1-2% nitric acid solution at 30-40°C into the coalescer, circulating it for 1-2 hours. Drain the acid solution and rinse thoroughly with clean water until the pH is neutral. Finally, soak the coalescer in a 5% hydrogen peroxide solution for 1 hour, drain, and rinse with clean water to restore normal operation.

[0055] This method for removing TOC from industrial-grade hydrogen peroxide solution uses a combined cooling-filtration-two-stage coalescence process to reduce the TOC content in industrial-grade hydrogen peroxide to below 80 ppm. The cooling process improves the thermal stability of hydrogen peroxide and reduces the risk of decomposition. The coalescence removal process is less susceptible to external factors, resulting in stable and reliable product quality. This method also eliminates the generation of large amounts of waste liquid, and the coalesced material can be recycled, reducing the amount of hazardous waste to be disposed of.

[0056] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for removing TOC from an industrial-grade hydrogen peroxide solution, characterized in that: The method comprises the following steps: S1, cooling treatment: the industrial-grade hydrogen peroxide solution produced at the bottom of the extraction tower is heat exchanged with the pure water to be entered into the extraction tower through a heat exchanger, and then further cooled to 15-25°C through a low-temperature water cooler to reduce the solubility of TOC in the hydrogen peroxide solution; S2, microfiltration treatment: filtering the hydrogen peroxide solution after cooling in step S1 through a high-precision filter with a pore size of 1 μm to remove some free TOC and particulate impurities; S3, a primary coalescence treatment; introducing the hydrogen peroxide solution filtered in step S2 into a primary hydrophilic oleophobic coalescer, and coalescing and separating the oil phase TOC in the solution from the aqueous phase hydrogen peroxide solution by the coalescing material in the primary hydrophilic oleophobic coalescer, thereby reducing the TOC content in the hydrogen peroxide solution to no more than 100 ppm; S4, secondary coalescence treatment; introducing the hydrogen peroxide solution treated in step S3 into a secondary hydrophilic and oleophobic coalescer for further coalescence separation by a coalescing material, so that the TOC content in the hydrogen peroxide solution is further reduced to no more than 80 ppm; S5, oil phase recovery: collect the oil phase TOC separated in step S3 and step S4 and transport it to the extraction tower for reuse.

2. The method for removing TOC from an industrial-grade hydrogen peroxide solution according to claim 1, wherein: The agglomerated material is prepared from the following components: Polypropylene, polyester, glass fiber or a mixture thereof as the skeleton material, accounting for 40 to 70% of the total weight of the agglomerated material; Polyvinyl alcohol, hydroxymethyl cellulose or silicate as the hydrophilic component, accounting for 10 to 25% of the total weight of the agglomerated material; Polytetrafluoroethylene, polyvinylidene fluoride or perfluoroallyl ethyl ether as the oleophobic component, accounting for 15 to 35% of the total weight of the coalescing material; The surfactant, pH regulator or antioxidant is used as a functional additive, accounting for 2 to 10% of the total weight of the agglomerated material.

3. The method for removing TOC from an industrial-grade hydrogen peroxide solution according to claim 1, wherein: In step S2, the filtration pressure of the high-precision filter is 0.2-0.3 MPa, and the filtration flow rate is 5-15 m / h.

4. The method for removing TOC from an industrial-grade hydrogen peroxide solution according to claim 1, wherein: In step S3, the liquid residence time of the first-stage hydrophilic-oleophobic coalescer is 15 to 25 minutes, and the operating pressure is 0.15 to 0.25 MPa.

5. The method for removing TOC from an industrial-grade hydrogen peroxide solution according to claim 1, wherein: In step S4, the liquid residence time of the secondary hydrophilic-oleophobic coalescer is 10 to 15 minutes, and the operating pressure is 0.1 to 0.2 MPa.

6. The method for removing TOC from an industrial-grade hydrogen peroxide solution according to claim 1, wherein: The method for removing TOC from an industrial-grade hydrogen peroxide solution also includes a regeneration step for the coalescing material, which includes backwashing regeneration and chemical cleaning regeneration. The backwashing regeneration is performed when the pressure difference of the first-level hydrophilic and oleophobic coalescer or the second-level hydrophilic and oleophobic coalescer increases to 1.5 times the initial value, and the coalescing material is reversely flushed for 30 to 60 minutes using hot water at 50 to 60°C. The chemical cleaning regeneration sequentially uses a nitric acid aqueous solution and a hydrogen peroxide solution to clean the coalescing material.

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